C.O.R.N. Newsletter: 2015-32

This season, farmers are at high risk of having a field fire during corn harvest.

The conditions present during harvest season include dry plant material and grain dust that are highly combustible.  Hot equipment or engine sparks are great ignition sources.  It is not uncommon for exhaust pipes or catalytic converters to exceed 1,000°F. Add a little wind and there is a perfect opportunity for a field fire.  

Being prepared to handle field fires is important for all workers and transport drivers.  Combines, tractors, grain trucks, and pick-ups should all be equipped with a trustworthy fire extinguisher as the first lines of defense.  Combines should carry an ABC 10-pound fire extinguisher in the cab and a larger 20-pound unit at the ground level. Tractors and trucks are recommended to have a 5-pound minimum extinguisher available.  These extinguishers should be in EACH vehicle in the field.  Nothing is worse than watching the combine go up in flames while you're running to the end of the field to retrieve the fire extinguisher on the grain cart.  Having an extinguisher on each piece of equipment ensures you will be ready to react on the first signs of smoke.

Don't get caught with a false sense of security.

If you follow the recommendations and own enough fire extinguishers, then you must also follow the maintenance recommendations.  Check the pressure gages periodically, making sure the needle remains in the "charged" zone.  If a unit has been partially discharged, it must be fully recharged before using it again.  Even a slight discharge can create a gap in the internal seal of the extinguisher valve, causing the pressure to leak out.  The pressure needle may linger in the charged zone; however there may not be adequate pressure to expel the contents.

Extinguishers could use a little shake a few times a year. By inverting the extinguisher and shaking it several times each season makes sure the powder doesn’t get lodged at the bottom of the unit. Equipment vibrations are notorious for compacting the reactive ingredients of fire extinguishers; making them worthless when they are needed.

Extinguishers should also be inspected periodically by a fire professional.  Fire service companies can be found in community directories.  Your local fire department or insurance company can also point you in the right direction for service companies.  Some extinguishers are not designed to be refilled, or are too old to be refilled.  These units should be replaced when they expire.  Having these old extinguishers around does no good when the time comes to pull the pin.

Follow other fire prevention practices.

It is also important to keep machinery in good repair.  Apply grease to bearings and oil chains regularly to reduce friction.  It is recommended to perform maintenance checks at the end of the day, rather than at the beginning, to detect any hot smoldering areas that may break out into flames overnight.   

Keep machinery clean and free from plant materials, especially around the wrap points.  Wipe up any fuel or oil leaks to eliminate additional fuel sources; and do not leave oily rags on equipment or in the cab.  

Use an air compressor or leaf blower to remove crop residue, and a pressure washer to remove built up oil or caked-on grease.

Take time to cool down the equipment each night, and check for any hot spots.  These steps can make a difference to save equipment, facilities, commodities, and lives.

Being prepared to handle field fires is important for all workers.  Having machinery equipped with a trustworthy fire extinguisher is one of the first lines of defense.

Be fire smart, and safe harvesting.

Fall is an excellent time to test soil pH and determine whether any lime needs to be applied for future crops. Proper soil pH is important for nutrient availability, herbicide activity, and crop development. For most soils, additional lime is not needed every year. Consider these points before liming your fields:

·       Do I need lime? Each year we hear stories of people adding lime to their fields without a soil test. The grower has a source of free waste-product lime that they pick up and apply to their fields. In many cases their soil pH was fine, but they did not want to pass up a "good deal". Without knowing the soil pH, a grower may inadvertently raise their soil pH to the high 7's. At this elevated pH, certain nutrients may become limited and the productivity of their crop may be reduced and require special management practices. Western Ohio has the greatest risk of elevating soil pH from careless applications of lime. A soil analysis is the best step to determine if a field needs lime.

·       What is the pH of my subsoil? Generally a laboratory recommends lime when the soil pH drops two to three units below the desired value. The desired value depends upon the crop and the pH of the subsoil. In parts of Ohio where the subsoil pH is less than 6.0 for mineral soils (eastern Ohio), additional lime is recommended after the soil pH drops to 6.2 for corn and soybean, and 6.5 for alfalfa. In other parts of the state (generally western Ohio), the subsoil pH for mineral soils is greater than 6.0 and lime is not needed until the soil pH drops below 6.0 for corn and soybeans, and 6.2 for alfalfa. Private laboratories may not take in account the subsoil pH and use recommendations based on a subsoil pH less than 6.0 for all parts of the state, possibly recommending lime applications several years earlier than needed for some areas.

·       What is the Effective Neutralizing Power of my lime source? An important item from a lime analysis report is the Effective Neutralizing Power (ENP) value, which is required for material sold as lime for agricultural purposes in Ohio. This value allows a producer to compare the quality among lime sources because ENP considers the purity, neutralizing power (including fineness) and moisture content. In other words, the ENP tells you how much of that ton of lime actually neutralizes soil acidity. The unit for ENP is pounds/ton (be careful not to use %ENP, which may also be on a lime analysis report). The ENP allows a producer to compare different lime sources because they can now determine price per pound or ton of actual neutralizing material.

·       Should I use “hi cal” or dolomitic lime? In most situations it does not matter, so a producer can select the least expensive of the two lime sources. Transportation is often the largest cost of a lime material, so generally the closest lime source (quarry) is often the most economical.

Several parts of the state are historically low in soil magnesium (eastern and southern Ohio). Adequate soil magnesium is important to reduce the risk of such problems as grass tetany for grazing animals. Soil test magnesium levels need to be greater than 50 ppm (100 lb) for optimal corn, soybean, wheat, and alfalfa production. Often areas low in magnesium also need lime, which has made the application of dolomitic lime an economic solution for both concerns.

The ratio between calcium and magnesium is important. Soils should contain more calcium than magnesium. Extensive research has shown that crops yield the same over a wide range of calcium to magnesium ratios and will not affect crop production as long as the calcium to magnesium ratio is larger than 1. High calcium lime should be used in situations where the soil test calcium to magnesium ratio is less than 1, or in other words, the soil magnesium levels are greater than the soil calcium levels. We have not observed any Ohio soil tests where the magnesium levels are above the calcium levels. Also keep in mind that almost all dolomitic lime sources will contain more calcium than magnesium. Unfortunately, some producers have been led to believe that magnesium levels in dolomitic lime may be undesirable. The Ohio State University is currently investigating the importance of calcium to magnesium ratios in crop production since the last Ohio research was completed in the early 1980s. For now, the focus should be selecting lime on its Effective Neutralizing Power (ENP) rather than its calcium level.

·       How about gypsum as a lime source? Gypsum is not a lime source. It does not have the right chemical composition to neutralize soil acidity, such as carbonate (gypsum is calcium sulfate). Gypsum is used as an amendment for soil physical properties and/or as a fertilizer providing calcium and sulfur.

In summary, make sure you take a soil test to determine if lime is needed, determine if magnesium is needed, know the historic pH of your subsoil, and then use the ENP to select the most cost effective lime material. A soil test every three to four years will determine the lime requirements for your fields. Additional information on ENP and lime sources and liming rates may be found at the following location:https://agcrops.osu.edu/specialists/fertility/fertility-fact-sheets-and-bulletins/AGF505.pdf